The present invention relates to an axle suspension on a vehicle frame, in particular an axle suspension for a mobile working machine or a mobile crane.
An axle suspension typically describes the axle bracket connecting the two wheel carriers of a vehicle and their coupling to a vehicle frame. It is necessary that due to the changing level of a subsurface the suspension be movable with respect to a vehicle frame. Typically, there are provided damping elements in the form of so-called spring struts which provide for a compression or rebound of the axle bracket with the wheel carriers with respect to a vehicle frame. In general, an axle suspension comprises two lower longitudinal links extending substantially in longitudinal vehicle direction and two upper diagonal links. The lower longitudinal links are arranged on the underside and the diagonal links on the upper side of the axle bracket. The axle bracket itself is transversely oriented in longitudinal direction. In combination, the lower longitudinal links and the upper diagonal links absorb forces from the moments acting on the axle bracket as a result of the drive or on braking of the vehicle. Due to their inclined position, the diagonal links arranged on the upper side of the axle bracket not only absorb the forces produced in longitudinal direction, but also the forces produced in transverse direction and introduce the same into the vehicle frame.
Alternatively, the upper and the lower longitudinal links can each be designed parallel to each other. The support of the axle or axle bracket in transverse vehicle direction then can be effected by a transverse link or Panhard rod. A detailed description of a conventional axle suspension will be made in the discussion of FIGS. 1 and 2.
As explained already, acting against a torque caused by the drive or by braking hence requires that both on the side of the axle or axle bracket facing the vehicle frame and on the far side steering rods are provided, which however prevent a further lowering of the vehicle frame in direction of the axle bracket. The lower end of the vehicle frame accordingly cannot extend in direction of the axle bracket, as the steering rods articulated on the upper side of the axle bracket have a certain space requirement.
In certain vehicle types, however, in particular in a mobile crane, it is advantageous when the height of the vehicle frame can be increased without limitation of the ground clearance, without increasing the weight of the vehicle frame, in order to achieve a maximum strength as well as stiffness by increasing the moment of inertia and resistance without exceeding the maximum vehicle height.
Furthermore, it is advantageous to provide an axle suspension which as compared to a conventional axle suspension creates a more stable vehicle with the same vehicle weight and thereby permits a higher lifting capacity. Alternatively, a lower weight of the vehicle might be desirable with the same stability.